Question 17.6.1: Predict the number of signals and multiplicity of the respec......
Predict the number of signals and multiplicity of the respective signals in the following compounds.
(i) \quad CH_3CH_3\quad (ii) \quad Cl—CH_2—CH_2—CH_2—Cl
(iii) \begin{matrix} CH_2 &—& O\\ | &\quad & | \\CH_2& —&CH_2\end{matrix} \quad \quad
(iv)\quad \begin{matrix}{CH_3}& \quad \\ \quad {\diagdown} & \quad \\ \quad &CH—C≡N\\ \quad \diagup & \quad \\CH_3 & \quad \end{matrix}\quad
\begin{matrix} (v) \quad CH_3 & — &C & \xlongequal[]{} CH_2\\ \quad & \quad & | & \quad \\ \quad & \quad & Cl & \quad \end{matrix}
(i) One signal Singlet as all hydrogens are equivalent
(ii) Cl— \overset{a}{CH_2}— \overset{b}{CH_2}— \overset{a} {CH_2}—Cl
2- signals; signal of CH_2 (b) appears as a quintet (5 peaks n +1 rule; 4 + 1 = 5 and that of CH_2 (a) protons as a triplet (n+1 rule; 2 + 1=3)
(iii) \begin{matrix}^a CH_2 &—& O\\ | &\quad & | \\^bCH_2& —&\underset{a}CH_2\end{matrix} \quad \quad
2–signals A four proton triplet and a two proton quintet (5 peaks)
(iv)\quad \begin{matrix}\overset{b}{CH_3}& \quad \\ \quad \quad {\diagdown} & \quad \\ \quad & \overset{a}CH—C≡N\\ \quad \quad \diagup & \quad \\\overset{b}{CH_3} & \quad \end{matrix}\quad
2– signals A six proton doublet and a one proton septet
(v) \begin{matrix} \overset{c}{CH_3} & & \quad \overset{a} H\\ \quad \quad \diagdown & & \diagup \quad \\ & C \xlongequal[]{} C & \\ \quad \quad \diagup & & \diagdown \quad \\ Cl & & \underset{b}H \end{matrix}
3– signals H_a and H_b cause splitting of signals and each appears as a doublet. CH_3 appears as a singlet.